wind solution

8/6/2019 Wind Solution

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Wind Turbine Electronic Furling and Yaw Control

Proprietary and Confidential Property of Lauritzen Inc.


Curtis Cole

Lauritzen Inc.June-2009

Objective:To control a wind turbine to optimally harvest energy and

protect the system components. The system must point

the turbine into the wind to collect energy and furl byturning out of the wind when appropriate. The system

must be fully accountable and report system failures and

faults.

System Description:A typical wind driven electricity generator has the following components [Figure 1]: aturbine with blades attached to a generator or dynamo to product AC or DC electricity;

possibly a rectifier to convert AC to DC; an inverter to convert DC to AC suitable for

tying to the grid; and sensors to monitor the turbines speed, direction, and powerproduction. An electronically controlled system also needs an anemometer and wind

vane to measure ambient conditions; a motor to point the turbine in a specific direction;and a controller to command the motor based on the sensor inputs and control algorithms.

The controller, motor, and sensors must have a power source independent of the grid

power. When the grid power fails, the system must have adequate power to shutdown theturbine and lock it into a stow configuration.

Generator or

dynamo

AC to DC

Rectifier

DC to ACInverterYaw direction

motor





Figure 1: simplified wind turbine

A Lauritzen Inc. Kári Wind Turbine Controller is capable of monitoring and managingthe operation of an electronic furling wind turbine. It monitors the turbine RPMs, turbine

direction, AC generation, grid-tie and inverter status while also receiving data from

weather station component such as an anemometer and wind vane. Kári then drives

commands to the turbine’s position (yaw) motor.

Figure 3: Kári controller

The Kári controller is connected to the Lauritzen Inc. servers through a 10Mb Ethernet

cable, and provides periodic updates of system status. Similarly, a connection can beestablished from the Lauritzen Valhalla server to the Kári controller to providediagnostics, on-line technician support, as well as remote software updates.

System Operation:The operation of a typical wind turbine is the same around the clock. It does not show

the ephemeral change typical of a PV or thermal hot water system driven by solar

radiation. However, winds often do follow a regular pattern over a day.

In the normal operation of a wind turbine, the controller continuously points the turbine

directly into the wind to harvest the most energy possible from the wind. System

parameters control how often the system will move to chase a new wind direction andrequire a minimum step size for a move to avoid insignificant adjustments.





Chart 1: Turbine Angle (range -540 to +540) vs Wind Direction (0-359)

In the lightest of winds, it is not useful to point the turbine into the wind as so littleenergy is available. So system parameters specify a minimum wind speed to prevent the

turbine moving around while there is little or no wind. At the other extreme, since the

kinetic energy in wind relates to the cube of the velocity, high winds can damage aturbine and its generator.

Chart 2: Turbine RPMs

Electronic furling refers to turning a turbine away from the wind to collect less energy

and slow the rotation speed. In high winds, or when a generator is turning at a speed

above a system parameter, the controller can turn the turbine a number of degrees out of the wind to produce energy at a safe turbine RPM. Under more severe conditions, the

system is shutdown by turning 90 degrees to the wind, waiting for the rotation to drop

low, and applying a brake to the generator.

Finally, other external effects such as grid failure, inverter failure, or the presence of an

operator can require the system to go into a safety shutdown. Control algorithms in theKári Controller implement these wind following, electronic furling and safety

requirements [Figure 3].





Figure 3: wind turbine control block diagram

The Kári Controller sends sensor data, events, and alarms to the Lauritzen Inc. Valhalla

server. Field support teams receive notifications of a turbine’s unusual behavior.

Through a remote diagnostic session, service technicians can monitor and diagnose manyfield problems without the expense of driving to a remote wind farm.

In Norse mythology, Kári is the personification of wind.

Turbine RPMand Direction

Wind Speedand Direction

Motor Commandand Safety Brake

Inverter and Grid Status

PID and Control Algorithms

Kári Controller

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